1. Field of the Invention
The invention is directed to a method for the internal electrical insulation of a substrate for a power semiconductor module. Such power semiconductor modules comprise a plastic framelike insulating housing with a cap and an insulating substrate. At least one conductor track is mounted on the substrate and at least one power semiconductor component is mounted on the conductor track. The power semiconductor component is connected to connection elements, further conductor tracks, and/or further power semiconductor components as necessary in the circuit with which it is to be used. Bond connections are the state of the art for such connections that are internal to a module.
2. Description of the Related Art
The state of the art in internal insulation of such power semiconductor modules is potting the modules with a dielectric insulation compound, which comprises either so-called hard casting or so-called soft casting, or a combination of the two. Because of the chemical composition of the hard casting compound and its attendant health risks, hard casting is being used less and less. Variously embodied silicone rubbers have become established as the state of the art for soft casting.
Often, two-component silicone rubber variants are used that are not mixed in a suitable device until just before the power semiconductor module is filled. Filling power semiconductor modules and hence internally insulating them is done up to a fill level that assures that all the relevant components to be insulated are securely covered.
A disadvantage of the aforementioned internal insulation of power semiconductor modules in the prior art is that a high proportion of the potting compound used is not truly necessary for insulation but instead is disposed inside the power semiconductor module solely for the sake of creating a homogeneous filling.